On the relation between supersoft X-ray sources and VY Scl stars: The cases of V504 Cen and VY Scl

We summarize our optical monitoring program of VY Scl stars with the SMARTS telescopes, and triggered X-ray as well as optical observations after/during state transitions of V504 Cen and VY Scl.Comment: 4 pages, Proc. of workshop "SuperSoft X-ray Sources - New Developments", ESTEC/Villafranca, May 2009, to appear in A

Cumulant ratios in fully developed turbulence

In the context of random multiplicative cascade processes, we derive analytical solutions for one- and two-point cumulants with restored translational invariance. On taking ratios of cumulants in ln epsilon, geometrical effects due to spatial averaging cancel out. These ratios can successfully distinguish between splitting functions while multifractal scaling exponents and multiplier distributions cannot.Comment: 9th Workshop on Multiparticle Production (Torino), 9 pages latex, incl 9 figs and espcrc2.st

Density correlators in a self-similar cascade

Multivariate density moments (correlators) of arbitrary order are obtained for the multiplicative self-similar cascade. This result is based on the calculation by Greiner, Eggers and Lipa (reference [1]) where the correlators of the logarithms of the particle densities have been obtained. The density correlators, more suitable for comparison with multiparticle data, appear to have even simpler form than those obtained in [1].Comment: 9 pages, 3 figures, uses epsfig.st

A novel scenario for the production of antihyperons in relativistic heavy ion collisions

We elaborate on our recent suggestion on antihyperon production in relativistic heavy ion collisions by means of multi-mesonic (fusion-type) reactions. It will be shown that the (rare) antihyperons are driven towards chemical equilibrium with pions, nucleons and kaons on a timescale of 1--3 fm/c in a still moderately baryon-dense hadronic environment.Comment: 4 pages, 3 figures, Contr. to QM2001: 15th. International Conference on Ultra-Relativistic Nucleus-Nucleus Collision

The benefit of simultaneous seven-filter imaging: 10 years of GROND observations

A variety of scientific results have been achieved over the last 10 years with the GROND simultaneous 7-channel imager at the 2.2m telescope of the Max-Planck Society at ESO/La Silla. While designed primarily for rapid observations of gamma-ray burst afterglows, the combination of simultaneous imaging in the Sloan g'r'i'z' and near-infrared JHK bands at a medium-sized (2.2m) telescope and the very flexible scheduling possibility has resulted in an extensive use for many other astrophysical research topics, from exoplanets and accreting binaries to galaxies and quasars.Comment: 26 pages, 22 figure

Importance of multi-mesonic fusion processes on (strange) antibaryon production

Sufficiently fast chemical equilibration of (strange) antibaryons in an environment of nucleons, pions and kaons during the course of a relativistic heavy ion collision can be understood by a `clustering' of mesons to build up baryon-antibaryon pairs. This multi-mesonic (fusion-type) process has to exist in medium due to the principle of detailed balance. Novel numerical calculations for a dynamical setup are presented. They show that - at maximum SPS energies - yields of each antihyperon specie are obtained which are consistent with chemical saturated populations of T approximately 150-160 MeV, in line with popular chemical freeze-out parameters extracted from thermal model analyses.Comment: 14 pages, 8 figures; new version in standard reftex; version of proceedings attached as postscript file; invited talk at CRIS2002, 4th Catania Relativistic Ion Studies, Exotic Clustering, June 10-14, 200